Nebraska constitution
Article VIII: revenue
Section 4

Except as to tax and assessment charges against real property remaining delinquent and unpaid for a period of fifteen years or longer, the Legislature shall have no power to release or discharge any county, city, township, town, or district whatever, or the inhabitants thereof, or any corporation, or the property therein, from their or its proportionate share of taxes to be levied for state purposes, or due any municipal corporation, nor shall commutation for such taxes be authorized in any form whatever; Provided, that the Legislature may provide by law for the payment or cancellation of taxes or assessments against real estate remaining unpaid against real estate owned or acquired by the state or its governmental subdivisions.